Cardiac surgery often involves replacement of the natural aortic valve, or the aortic root and ascending aorta, or both, with the corresponding prostheses. Blood flow through the aortic valve is influenced by the corresponding flow field in, and around, the aortic root. There exists the need for a methodology that permits analysis of the cumulative hemodynamic performance of aortic valve, aortic root and ascending aorta prostheses. A numerical, two-dimensional pulsatile blood flow model that accounts for fluid interaction with bioprosthetic aortic valve leaflets, and for flow in the sinuses of Valsalva and in the ascending aorta, will be developed in Phase I of this study. The hemodynamic performance of a typical bioprosthetic aortic valve will be evaluated in conjunction with ascending aorta grafts with, and without the sinuses. The effects of variation in the geometry, and dimensions, of the sinus on bioprosthetic valve hemodynamics will also be studied. In Phase II, the model will be refined, and extended for three dimensional simulations. Model validation will be done in collaboration with a leading experimental cardiovascular research group. The theoretical simulations will be used for developing design criteria for ideal- aortic root and for improved ascending aorta prostheses.